The invention relates to an apparatus for locking band hoops on packages by permanent deformation of two superimposed portions of a flexible hooping band. The deformation of the portions is brought about by pressing down a die arranged in raisable and lowerable manner over the portions. The bottom of the die is fixed to a pressure plate which is guided in the casing of the apparatus and toward a punch mounted in a base plate of the apparatus and positioned below the portions.
There are fundamentally two groups of known apparatus for locking band hoops. In the first group, locking is accomplished by means of a locking sleeve which is placed over the superimposed portions of the hooping band and is deformed together with the band portions to form a non-detachable connection. In the second group, which apparatus is used mainly for locking flexible metallic bands or strips, locking takes place without a sleeve, i.e. through reciprocal permanent deformation of the superimposed portions of the hooping band.
In the case of the second group of apparatus, the forces to be applied for deforming the superimposed portions of the hooping band are very large because a non-detachable connection has to be produced without using a locking sleeve. To this end, the band portions are placed between a punch mounted in the base plate of the apparatus and a raisable and lowerable die spaced above the punch. The die is pressed down with great force onto the band portions either manually or by means of a power drive until the permanent deformation of the band portions necessary for the non-detachable connection is achieved.
In order to obtain a permanent non-detachable connection between the band portions, it is important that the movable die is precisely aligned with the punch mounted in the base plate in order to bring about a perfect cooperation between the protuberances and depressions arranged in both these tools. However, this is not sufficient for obtaining a suitable connection if the force applied is insufficient. In known apparatus of this type, the necessary force is provided through force transmission linkages, such as toggle linkages. When such transmission linkages are used within a small lifting or stroke range, rapidly increasing forces are exerted. If the stroke travel is set too far, the resulting excessive force can lead to the destruction of the apparatus during the locking process. If the stroke travel setting is made too short, the necessary minimum deformation for the locking process is not obtained.